In other words, you are impotent when you lack self-control. Thus, being impotent is not just a matter of lacking some sort of vital energy but also of not being strong enough to control your vital energy, even if you have plenty of it.

So you lack true power when you cannot control yourself.

Our culture glorifies excess when in fact excess is impotence. This idea of excess as weakness is countercultural in our culture, as it was in much of Roman culture, especially as the empire became richer and unchallenged.